Negative Electrode Current Collector and Preparation Method Therefor, Negative Electrode Plate, Lithium Metal Battery, and Electrical Apparatus

The application is a continuation of International Application No. PCT/CN2024/075300, filed on Feb. 1, 2024, which claims priority to Chinese Patent Application No. 202311196336.5 filed on Sep. 18, 2023 and entitled “NEGATIVE ELECTRODE CURRENT COLLECTOR AND PREPARATION METHOD THEREFOR, NEGATIVE ELECTRODE PLATE, LITHIUM METAL BATTERY, AND ELECTRICAL APPARATUS”. The entire contents of the above patent applications are incorporated herein by reference.

The present application relates to the field of batteries, more specifically to a prepared negative electrode current collector and a preparation method therefor, a negative electrode plate, a lithium metal battery, and an electrical apparatus.

Lithium-ion batteries have developed tremendously in recent years. In lithium-ion batteries, graphite is usually used as a negative electrode active material, which has a limited theoretical capacity, limiting the energy density of the lithium-ion batteries. In lithium metal batteries, as a special type of lithium-ion batteries, high-energy-density lithium metal is used as a negative electrode active material and is considered to be one of the important development directions of lithium-ion batteries.

The surface of the negative electrode current collector is usually provided with a lithium-philic plating layer to facilitate the deposition of lithium metal. Existing plating layers easily fall off during the cycling of lithium metal batteries, which seriously threatens the performance of lithium metal batteries. Therefore, how to improve the stability of a lithium metal negative electrode current collector has become an urgent technical problem to be solved.

In view of the above technical problems, the present application aims to provide a negative electrode current collector and a preparation method therefor, a negative electrode plate, a lithium metal battery, and an electrical apparatus. The negative electrode current collector prepared by this method, when applied to a lithium metal battery, can effectively improve the stability of the negative electrode current collector and help improve the cycling performance of the lithium metal battery.

In a first aspect, a method for preparing a negative electrode current collector is provided, comprising: preparing a plating film on a copper substrate; and subjecting the copper substrate prepared with the plating film to an annealing treatment at a preset temperature T to obtain the negative electrode current collector. The plating film comprises a lithium-philic metal.

In an embodiment of the present application, the copper substrate is subjected to an annealing treatment after the plating film is prepared, and the plating film comprises a lithium-philic metal. Thus, the negative electrode current collector obtained after annealing comprises a copper substrate and a plating layer arranged on the copper substrate. The bonding force between the plating layer and the copper substrate in the negative electrode current collector is enhanced, thereby improving the stability of the negative electrode current collector. The current collector, when applied to a lithium metal battery, does not easily fall off during the cycling of the battery, which effectively improves the cycling performance of the lithium metal battery. In addition, the annealing treatment also helps to make the plating layer more evenly distributed on the surface of the copper substrate. Therefore, when applied to a lithium metal battery, it can make the deposition of the lithium metal more even, reduce the possibility of generation and growth of lithium dendrites, and improve the cycling performance of the lithium metal battery.

In one possible implementation, an annealing atmosphere of the annealing treatment comprises at least one of nitrogen, argon, a nitrogen-hydrogen mixed gas, and a mixed gas of an inert gas and hydrogen.

In the embodiments of the present application, by selecting the above atmosphere of the annealing treatment, the possibility of oxidation of the current collector and the plating film can be effectively reduced.

In one possible implementation, in the mixed gas of the inert gas and hydrogen, the volume content of hydrogen, V%, satisfies 1%≤V%≤2%, optionally, 1%≤V%≤1.5%.

In the embodiments of the present application, by using hydrogen as a reducing gas in the mixed gas, the possibility of oxidation of the current collector and the plating film during the annealing treatment can be further reduced. Furthermore, controlling the volume content of the reducing gas in the mixed gas within an appropriate range helps to reduce the probability of safety accidents caused by an excessively high content of the reducing gas while reducing the possibility of oxidation of the current collector and the plating layer.

In one possible implementation, the lithium-philic metal comprises at least one of Sn, Mg, Zn, Bi, Pb, Au, Ag, or Al.

In one possible implementation, the copper substrate includes copper foil and foam copper; optionally, the copper substrate is foam copper.

In the embodiments of the present application, three-dimensional porous foam copper can be selected as the copper substrate. The foam copper has a relatively large specific surface area, so that the current density on the current collector is relatively small, which can effectively improve the precipitation of lithium and the growth of lithium dendrites.

In one possible implementation, before the annealing treatment, the method further comprises rolling the plated copper substrate.

In one possible implementation, where the lithium-philic metal includes Sn, T satisfies 200° C.≤T≤800° C.; or where the lithium-philic metal includes Mg or Zn, T satisfies 500° C.≤T≤1000° C.; or where the lithium-philic metal includes Bi, T satisfies 450° C.≤T≤650° C.; or where the lithium-philic metal includes Pb, T satisfies 600° C.≤T≤800° C.; or where the lithium-philic metal includes Au, T satisfies 900° C.≤T≤1100° C.; or where the lithium-philic metal includes Ag, T satisfies 800° C.≤T≤1000° C.; or where the lithium-philic metal includes Al, T satisfies 600° C.≤T≤700° C.

In the embodiments of the present application, depending on the type of the lithium-philic metal in the plating film, different preset temperatures T are set for the annealing treatment. Depending on the type of the lithium-philic metal in the plating film, the preset temperature T is controlled within an appropriate range, so that the lattice structure of the copper substrate will not be destroyed while the bonding force between the plating layer and the copper substrate is improved after annealing. When applied to a lithium metal battery, it does not affect the performance of the lithium metal battery.

In one possible implementation, T is greater than or equal to the melting point of the lithium-philic metal.

In the embodiments of the present application, setting T to be greater than or equal to the melting point of the lithium-philic metal is more conducive to mutual diffusion between the lithium-philic metal and the copper substrate, which helps to further improve the bonding force between the plating layer and the copper substrate.

In one possible implementation, the negative electrode current collector is applied to a lithium metal battery.

In one possible implementation, the preparation of the plating film on the copper substrate comprises: preparing the plating film on the copper substrate by magnetron sputtering.

In one possible implementation, the areal density p of the plating film satisfies 2 g/m≤ρ≤4 g/m, optionally, 2 g/m≤ρ≤3 g/m.

In one possible implementation, the holding time t of the annealing treatment satisfies 20 min≤t≤60 min, optionally, 25≤t≤40 min.

In the embodiments of the present application, controlling the time of the annealing treatment within an appropriate range helps to facilitate the production and manufacturing of the current collector while obtaining a negative electrode current collector with improved cycling performance of the battery.

In one possible implementation, the preparation of the plating film on the copper substrate comprises: preparing the plating film on the copper substrate by chemical electroplating.

In one possible implementation, the areal density p of the plating film satisfies 1.5 g/m≤ρ≤3 g/m.

In one possible implementation, the holding time t of the annealing treatment satisfies 30 min≤t≤60 min.

In one possible implementation, where the lithium-philic metal includes Sn, T satisfies 700° C.≤T≤800° C.

In one possible implementation, the heating rate v of the annealing treatment satisfies 2° C./min≤v≤3° C./min.

In a second aspect, a negative electrode current collector is provided, which comprises a copper substrate and a plating layer arranged on the copper substrate. The plating layer comprises a lithium-philic metal and a lithium-philic metal-copper alloy.

In one possible implementation, the lithium-philic metal comprises at least one of Sn, Mg, Zn, Bi, Pb, Au, Ag, or Al.

In one possible implementation, the copper substrate includes at least one of copper foil and foam copper; optionally, the copper substrate is foam copper.

In one possible implementation, In one possible implementation, the negative electrode current collector is prepared by an annealing treatment, and the annealing temperature of the annealing treatment is preset temperature T. Where the lithium-philic metal includes Sn, T satisfies 400° C.≤T≤600° C.; or where the lithium-philic metal includes Mg or Zn, T satisfies 500° C.≤T≤1000° C.; or where the lithium-philic metal includes Bi, T satisfies 450° C.≤T≤650° C.; or where the lithium-philic metal includes Pb, T satisfies 600° C.≤T≤800° C.; or where the lithium-philic metal includes Au, T satisfies 900° C.≤T≤1100° C.; or where the lithium-philic metal includes Ag, T satisfies 800° C.≤T≤1000° C.; or where the lithium-philic metal includes Al, T satisfies 600° C.≤T≤700° C.

In one possible implementation, T is greater than or equal to the melting point of the lithium-philic metal.

In one possible implementation, the negative electrode current collector is applied to a lithium metal battery.

In one possible implementation, the plating layer is prepared by magnetron sputtering and an annealing treatment.

In one possible implementation, the plating layer is prepared by chemical electroplating and an annealing treatment.

In a third aspect, a negative electrode plate is provided. The negative electrode plate comprises the negative electrode according to any one possible implementation of the first aspect or a negative electrode current collector prepared by the method according to any one possible implementation of the second aspect.

In a fourth aspect, a lithium metal battery is provided. The lithium metal battery comprises the negative electrode plate according to any one possible implementation of the third aspect.

In one possible implementation, the negative electrode plate is the negative electrode current collector.

In a fifth aspect, an electrical apparatus is provided. The electrical apparatus comprises the lithium metal battery according to any one possible implementation of the fourth aspect.

Hereinafter, embodiments of the method for preparing a negative electrode current collector, the negative electrode current collector, the negative electrode plate, and the electrical apparatus according to the present application are specifically disclosed with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known items and repeated descriptions of actually identical structures are omitted. This is to avoid unnecessary redundancy in the following descriptions and to facilitate understanding by those skilled in the art. In addition, the drawings and subsequent descriptions are provided for those skilled in the art to fully understand the present application, and are not intended to limit the subject matter recited in the claims.

The “ranges” disclosed in the present application are defined in the form of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of the particular range. The range defined in this way may include or may not include end values, and may be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for specific parameters, it is understood that the ranges 60-110 and 80-120 are also expected. In addition, if the listed minimum range values are 1 and 2 and if the listed maximum range values are 3, 4, and 5, the following ranges can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present application, unless otherwise specified, the numerical range “a-b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range “0-5” indicates that all real numbers between “0-5” have been listed herein, and “0-5” is only a shortened representation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

In the description of the present application, it needs to be noted that unless otherwise specified, the “plurality of” means two or more; and the directions or position relationships indicated by the terms “above”, “below”, “left”, “right”, “inner”, “outer”, etc., are only provided to facilitate the description of the present application and simplify the description, rather than indicating or implying that the apparatus or element referred to must have a specific direction, or be constructed and operated in a specific direction, and therefore cannot be construed as limiting the present application. In addition, the terms “first”, “second”, “third”, etc., are only for the purpose of description, and cannot be construed as indicating or implying the relative importance.

Unless otherwise specifically specified, in the present application, the term “and/or” is inclusive. By way of example, the phrase “A and/or B” indicates “A, B, or both A and B”. More specifically, any one of the following conditions satisfies the condition “A and/or B”: A is true (or present) and B is false (or absent); A is false (or absent) and B is true (or present); or both A and B are true (or present). In this disclosure, unless otherwise specified, phrases like “at least one of A, B, and C” and “at least one of A, B, or C” both mean only A, only B, only C, or any combination of A, B, and C.

Unless otherwise specified, all the steps in the present application can be carried out, either in order or randomly, in some embodiments in order. For example, the method comprises steps (a) and (b), which means that the method may comprise steps (a) and (b) performed in order, or may comprise steps (b) and (a) performed in order. For example, reference to “the method may further include step (c)” indicates that step (c) may be added to the method in any order, for example, the method may comprise steps (a), (b), and (c), or steps (a), (c), and (b), or steps (c), (a), and (b), etc.

Unless otherwise specified, all the embodiments and optional embodiments of the present application can be combined with each other form new technical solutions.

Unless otherwise particularly specified, the following terms have the following meanings. Any undefined terms have their technically accepted meanings.

If mentioned, “lithium-philic metal” refers to a metal that can induce lithium deposition. Examples are Mg, Sn, Ag, etc.

If mentioned, “magnetron sputtering” refers to the phenomenon in which high-energy particles are used to bombard a solid surface, and atoms and molecules on the solid surface exchange kinetic energy with the incident high-energy particles and then sputtered out from the solid surface.